The present invention relates to a stamping-laminating apparatus and method adapted for manufacturing motor cores to consecutively stamping out core pieces from workpieces such as a hoop material and to laminate a predetermined number of core pieces per unit.
Such a stamping-laminating apparatus is disclosed in Japanese Laid-Open Patent Publication No. 2006-26735. The stamping-laminating apparatus includes a die and a punch. The punch is movably arranged along the same axis as the die and faces the upper surface of the die. A lateral pressure ring is arranged below the die. The lateral pressure ring is also arranged on the same axis as the die and located adjacent to the die. When the punch is lowered toward the die, a core piece is stamped out of a workpiece. The lateral pressure ring applies lateral pressure to a plurality of core pieces. A predetermined number of core pieces are laminated inside the lateral pressure ring. According to the method, lateral pressure is applied to the outer circumferential surfaces of the core pieces when the core pieces are laminated. This can bend the laminated core pieces so that the upper surface is concave. As a result, the flatness of the core pieces is degraded, and product accuracy may deteriorate.
To solve such problems, the stamping-laminating apparatus disclosed in Japanese Laid-Open Patent Publication No. 2006-26735 has a counter pressure applying mechanism below a die. The counter pressure applying mechanism applies a counter pressure toward the punch (upward) to stamped and laminated pieces from the side opposite to the punch (from below). This suppresses bending of the core pieces. In this stamping-laminating apparatus, a product discharging mechanism is arranged below the die. When a predetermined number of core pieces are laminated, the laminated core pieces are lowered to a position that corresponds to the product discharging mechanism, while being supported by the counter pressure applying mechanism. Thereafter, the product discharging mechanism discharges the laminated core pieces from the position on the counter pressure applying mechanism to a side.
According to the stamping-laminating apparatus, core pieces keep being stamped out and laminated during the period in which other laminated core pieces are lowered and discharged by the produce discharging mechanism while being supported by the counter pressure applying mechanism. In this case, the core pieces that are being machined do not receive counter pressure while the counter pressure applying mechanism is lowered. As a result, the curvature of the core pieces is changed, which lowers the product accuracy. To avoid such a drawback, stamping and laminating of core pieces need to be suspended during a period in which laminated core pieces are discharged. However, the discharge of laminated core pieces takes a certain amount of time. Therefore, if machining of core pieces is suspended during discharge of other core pieces, productivity will be lowered significantly.